Condenser



Filed Jan. 27, 1936 INVENTOR CORA/L-Z/S Del/W65 BY MAM,

ATTO RNEY Patented Feb. 28, 1939 UNITED STATES.

PATENT OFFICE simor to N. V. Philips Gloeilampenfabrieken,

Eindhoven, Netherlands Application January 27, 1936, Serial No. 60,942In Germany February 2, 1935 This invention relates to a rigid condenserfor radio purposes. For this purpose condensersof particularly lowcapacity, for example, of the order of magnitude of 1 F. which shouldhave 5 a value that can be determined accurately are often necessary. Itis common practice to constitute them by a substantially plate-shapedpiece of dielectric provided on both sides with electrodes applied byprojection or in any other suitable 10 manner. This suffers from thelimitation that the capacity often differs from the desired value. Thisdifficulty was obviated by balancing the capacity of the condensersafter manufacture until thedesired value was achieved, for examl5 pie,by removal of portions of the electrodes. This occupies considerabletime and is costly since comparatively circuitous measurements arenecessary., In. addition, comparatively considerable wastage ensues inthis manner since an excessive portion may easily be removed from theelectrode. In addition, various condensers are known consisting of atubular piece of insulating material. The electrodes may be constitutedby screws inserted in the hoods and having an adjustable relativespacing. Alternatively, the electrodes may be arranged axially, the tubeserving as the dielectric. In this case, the capacity can be altered bymoving one of the electrodes inwards or outwards. These constructionsare, 0 however, comparatively complicated and costly.

The invention has for its object to manufacture a condenser for radiopurposes which is simple and can be manufactured with great accuracy.

According to the invention, a condenser is composed of a rod ofinsulating material serving as the dielectric and having its endsprovided with metal hoods. The hoods are preferably applied by pressureso as to obtain a rigid body to which connecting wires can be secured ina simple manner.

It should be mentioned that condensers constituted by a piece ofinsulating material with electrodes arranged at the ends are known perse from the high tension industry where they serve for the potentialdistribution or as insulators or the like. Such condensers are, however,not very suited for radio p poses inter alia by reason of their largedimensions.

The insulating rod is preferably made of ceramic material having a highdielectric constant. For such rods use may be made of materialcontaining rutile, that is to say, titanium dioxide or a similarmaterial having a high dielectric constant.

It has been found that the condenser according to the invention can bemanufactured with great accuracy so that subsequent adjustment isunnecessary after manufacture.

Inorderthattbeinvmtionmaybeclearly understood and readily carried intoeflect one embodiment thereof will now be described more fully withreference to the accompanying drawns Referring to the single figure ofthe drawing, the dielectric I is preferably formed as a solid cylinder.Hoods 2 and 3 are secured in such manner, for example, by pressure, thatthere are practically no air gaps. The latter would bring about a heavyfall of the capacity. The hoods have secured to them in the usual mannerconnecting Wires 5 and 5. The condenser is made from a very fewcomponent members. In wholesale manufacture the capacity may easily bemaintained up to a few percent within the desired value. If a differentcapacity is desired, this may be achieved in a very simple manner by adifferent choice of the length of the core or of the properties of thematerial.

In one embodiment in which a. capacity of 2 F. was desired the length ofthe core was 13.;mms. and the diameter 4 mms. The height of the hoodswas 4 mms. and the dielectric constant E=80. In the case of E beingequal to 40 the capacity was found to be 0.9; F.

I claim:

1. A low capacity condenser for radio purposes, which is constituted bya small rod of dielectric material and by two metal hoods secured bypressure to the ends and serving as electrodes.

2. A low capacity condenser as claimed in claim 1, wherein thedielectric material is titanium dioxide having a high dielectricconstant.

' 3. A low capacity condenser as claimed in claim 1 wherein thedielectric material contains rutile. 36

4. A low capacity condenser for radio purposes which comprises a rod ofdielectric material both ends of which are beveled, two metallic hoodswith beveled ends secured by pressure to the ends of said rod andserving as electrodes.

5. A low capacity condenser for radio purposes which comprises a rod ofdielectric material both ends of which are beveled, two metallic hoodswith beveled ends secured by pressure to the ends of said rod andserving as electrodes, and an aperture in the ends of each hood having aconnection wire secured thereto.

6. A low capacity condenser for radio purposes which comprises a rod ofdielectric material, the length of which is substantially thirteenmillimeters and the diameter of which is four millimeters, two metallichoods with beveled ends secured by pressure to the ends of said rod andserving as electrodes, and an aperture inthe ends of each hood having aconnection wire CORNEHB n: LARGE.

